I do not see how foreign source income included in a W-2 is not taxable. I do not think it should be subtracted on Line 21. Edited to insert "not"
Further, if it is not taxable in the US, then you cannot claim a foreign tax credit because it has not been taxed by the US and another country.
You would need to know the amount of RSU included in your W-2 wages. After determining this amount, you will need to allocate the income by between foreign and US workdays between grant and vest. If 50% of your workdays during this time were in a foreign country, then 50% of your RSU income would be foreign source. US source income cannot be offset by foreign tax credits.
You would enter you W-2 as you normally would in TurboTax. Then you would go to Miscellaneous income to enter the amount of foreign source RSU income as a negative number on line 21, page 1 of your 1040.
Please follow the instructions below to report your foreign RSU income as a negative on line 21:
The you need to go to the foreign tax credit section of TurboTax to enter the foreign income (amount that you entered as a negative on line 21) so that you may take credit for the foreign taxes you already paid.
To include the amount of foreign taxes you paid, follow these steps for TTPremier: